title: Testosterone exacerbates hypertension and reduces pressure-natriuresis in male spontaneously hypertensive rats.
abstract: Studies were performed in intact male and female, gonadectomized male and female, and gonadectomized female rats given testosterone for 5 weeks to investigate the role played by testosterone in altered blood pressure control and pressure-natriuresis in male SHR. Serum testosterone levels reached a peak at 12 weeks of age in intact male SHR. Systolic blood pressure, measured weekly from 5 to 20 weeks of age, was similar between groups until 12 weeks of age when blood pressure became higher in males (195+/-3 mm Hg) than in females (168+/-3 mm Hg) or males castrated at 4 weeks (173+/-4 mm Hg). At 17 to 19 weeks direct measurement of arterial pressure in anesthetized rats confirmed that mean arterial pressure was higher in male (182+/-1 mm Hg) than in female (159+/-2 mm Hg) and castrated male SHR (159+/-2 mm Hg). In addition, testosterone (5 mg in Silastic pellets, SC for 5 weeks) administered to ovariectomized (ovx+T) females caused arterial pressure to increase by mm 11% (175+/-2 mm Hg), which was significantly higher than in intact female, castrated male, or untreated ovariectomized (ovx) female SHR (158+/-2 mm Hg). Acute pressure-natriuresis was blunted in male SHR compared with females, castrated males, or ovx females, in which this relationship was similar. Pressure-natriuresis was also blunted in ovx+T females as found in intact male SHR. These data support the hypothesis that male sex hormones contribute to the exacerbation of hypertension in SHR by reducing pressure-natriuresis.
authors.affiliation: Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson 39216-4505, USA. jfr@fiona.umsmed.edu
authors.forename: J F
authors.initials: JF
authors.lastname: Reckelhoff
authors.forename: H
authors.initials: H
authors.lastname: Zhang
authors.forename: J P
authors.initials: JP
authors.lastname: Granger
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006400:Hematocrit; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D006973:Hypertension / Q000503:physiopathology*; D007668:Kidney / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D008297:Male; D009318:Natriuresis / Q000187:drug effects*; D009919:Orchiectomy; D009929:Organ Size / Q000187:drug effects; D010052:Ovariectomy; D051381:Rats; D011918:Rats, Inbred SHR; D012079:Renal Circulation / Q000187:drug effects; D012727:Sex Characteristics; D013599:Systole; D013739:Testosterone / Q000097:blood / Q000494:pharmacology*; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D013739:Testosterone